JPH1118293A - Battery charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent charging efficiency from degrading due to a resistor for excessive current prevention when a capacitor battery is charged from a lead acid battery, and reduce charging time. SOLUTION: When a capacitor battery 3 is charged from a lead acid battery 2, the voltage of the capacitor battery 3 is measured, based on a signal from the voltage measuring instrument 5 of a charge controller 10. When the voltage of the capacitor battery 3 increases with the progress of the charging operation, an actuator 6 is driven so that the resistance value of the resistor 4 between the lead battery 2 and the capacitor battery 3 is decreased. As a result, when the voltage of the capacitor battery 3 increases, charging time can be reduced without degrading the charging efficiency which is due to a resistor for large current prevention of a fixed and high resistance value as in the conventional cases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a battery charger for charging a capacitor battery from a lead battery.

[0002]

2. Description of the Related Art Conventionally, lead batteries have been widely used as power sources for vehicles such as automobiles. In addition to such lead batteries, for example, a capacitor battery such as an electric double layer capacitor is mounted as a power source for an electric heating catalyst or the like. There is a system to do.

In a system in which a lead battery and a capacitor battery are mounted, usually, a lead battery having a large power supply capacity is charged to a capacitor battery having a small power supply capacity. A resistor is inserted between the capacitors to prevent an excessive current from flowing during charging when the voltage of the capacitor battery is reduced.

[0004]

However, since the resistance inserted between the lead battery and the capacitor battery is generally set to a large value from the viewpoint of preventing an excessive current, the charging of the capacitor battery proceeds. As a result, when the voltage of the capacitor battery rises, it causes a reduction in charging efficiency, which hinders a reduction in charging time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when charging a capacitor battery from a lead battery, it is possible to prevent a reduction in charging efficiency due to a resistor for preventing an excessive current and to shorten a charging time. It is an object of the present invention to provide a battery charging device that can be used.

[0006]

According to the first aspect of the present invention,
A battery charger for a power supply system comprising a lead battery and a capacitor battery, wherein the lead battery charges the capacitor battery. The battery charger is interposed between the lead battery and the capacitor battery, and has a resistance value according to an operation input. A variable resistor, and control means for measuring the voltage of the capacitor battery and performing an operation output for reducing the resistance value of the resistor in accordance with a rise in the voltage of the capacitor battery.

According to a second aspect of the present invention, in the first aspect, the resistance value of the resistor is continuously variable.

According to a third aspect of the present invention, in the first aspect of the present invention, the resistance value of the resistor can be changed stepwise.

That is, according to the present invention, when charging a capacitor battery with a lead battery, the resistance value of a resistor interposed between the lead battery and the capacitor battery is determined by:
The voltage is reduced in accordance with the rise in the voltage of the capacitor battery, and a decrease in the charging current with the progress of charging is prevented, thereby preventing a reduction in charging efficiency. In this case, it is desirable to use a resistor whose resistance value can be continuously changed or a resistor whose resistance value can be changed stepwise.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show a first embodiment of the present invention.
1 is an overall configuration diagram of a charging device, FIG. 2 is a flowchart of a charging control routine, and FIG. 3 is an explanatory diagram showing resistance setting.

In FIG. 1, reference numeral 1 denotes a charging device of a power supply system that includes a lead battery 2 and a capacitor battery 3 and charges the capacitor battery 3 with the lead battery 2. The charging device 1 includes a charging device. A resistor 4 for preventing excessive current at the time, a voltage measuring device 5 for measuring the voltage of the capacitor battery 3, a charge controller 10 for controlling charging, and the like are provided.

The lead battery 2 and the capacitor battery 3 have respective negative electrode terminals commonly connected to each other, and respective positive electrode terminals connected to each other via the resistor 4. The above voltage measuring device 5
Are connected in parallel. Further, the resistor 4 is, for example, a variable resistor of the Slackack type, and its slider is moved by an actuator 6 driven by the charge controller 10 so that the resistance value can be continuously varied. .

When charging the capacitor battery 3 from the lead battery 2, the charge controller 10 variably controls the resistance value of the resistor 4 in accordance with the voltage of the capacitor battery 3. CPU1
1, ROM 12, RAM 13, A / D converter 14,
An I / O interface 15 and the like are mainly configured by microcomputers connected to each other via a bus line. The voltage measuring device 5 is connected to the A / D converter 14, and the driving circuit 1 is connected to the I / O interface 15.
The actuator 6 is connected to the actuator 6 via the actuator 6.

Hereinafter, the charge control of the capacitor battery 3 by the charge controller 10 will be described with reference to the flowchart of FIG.

In this charge control routine, step S101
A / D-converts the signal from the voltage measuring device 5 to detect the voltage Vc of the capacitor battery 3, and in step S102, starts the charging of the capacitor battery voltage Vc and the charging of the lead battery 2 to the capacitor battery 3. Voltage Vmin
Compare with

Then, in step S102, Vc ≧ Vmi
If n, and the voltage of the capacitor battery 3 has not dropped, the routine exits. At this time, the resistor 4
Has a minimum resistance value in an initial state, so as to minimize power loss at the time of discharging from the capacitor battery 3 to a load (not shown).

On the other hand, in step S102, Vc <Vmin
In step S103, the process proceeds to step S103, where the resistance set value RSET of the resistor 4 is set by referring to the table based on the capacitor battery voltage Vc. In step S104, the actuator 6 is driven to set the resistor 4 to the resistance set value RSET. Then, the capacitor battery 3 is charged from the lead battery 2 via the resistor 4 having a resistance value corresponding to the voltage of the capacitor battery 3.

As shown in FIG. 3A, the resistance setting value RSET is a resistance value for preventing an excessive charging current when the voltage of the capacitor battery 3 is lowered. The resistance is set in advance so as to decrease linearly with the rise. A one-dimensional table as shown in FIG. 3B is referred to based on the capacitor battery voltage Vc, and the resistance set value RSET is set by interpolation calculation or the like.

Thereafter, the steps S104 to S1 are performed.
Proceeding to 05, the voltage Vc of the capacitor battery 3 is detected again, and it is checked whether the charging is completed by comparing the capacitor battery voltage Vc during charging with the voltage Vmax during full charging.
If the capacitor battery voltage Vc has not reached the voltage Vmax at the time of full charge, the above-described step S105
By returning to step S103 from above, the resistance set value RSET of the resistor 4 is reset, so that the capacitor battery voltage V
The charging is continued by decreasing the resistance value according to the rise of c.

By repeating the above process, the resistance value of the resistor 4 is finally reduced to the minimum value in the initial state. When the charging proceeds and the capacitor battery voltage Vc reaches the voltage Vmax at the time of full charging, the charging is performed. Step S1 above as completion
Exit the routine from 05.

As a result, the resistance value of the resistor 4 between the lead battery 2 and the capacitor battery 3 is reduced as the charging of the capacitor battery 3 progresses. As described above, the charging time can be shortened without lowering the charging efficiency due to the large resistance for preventing the excessive current.

FIGS. 4 and 5 relate to a second embodiment of the present invention. FIG. 4 is an overall configuration diagram of a charging device, and FIG. 5 is an explanatory diagram showing resistance setting.

The present embodiment differs from the first embodiment in that a resistor 4A for changing the resistance stepwise is employed instead of the resistor 4 capable of continuously changing the resistance value.

That is, as shown in FIG. 4, the resistor 4A of the present embodiment is of a type in which a circuit of a plurality of parallel resistors R1, R2,..., Rn is switched by a rotary switch SW. The lead battery 2 and the capacitor 3 can be directly connected without using a resistor. Then, the connection position of the rotary switch SW is switched by the actuator 6A controlled by the charge controller 10, and the resistor 4
Is stepwise varied.

The charge control of this embodiment is the same as that of the first embodiment, but as shown in FIG. 5A, the resistance set value Ri decreases stepwise as the capacitor battery voltage Vc rises due to charging. As described above, the resistance set value Ri of the resistor 4A with respect to the capacitor battery voltage Vc is stored in advance in a one-dimensional table as shown in FIG. 5B, and when setting the resistance set value Ri of the resistor 4A, Referring to the one-dimensional table based on the capacitor battery voltage Vc,
The resistance set value Ri of the resistor 4A is set.

Each of the resistors R1, R2,
, Rn are, for example, the maximum resistance value at which the resistor R1 can limit an excessive current at the time of charging, and the resistance values of the resistors R2,.
Is connected to the resistor R1, and as the voltage of the capacitor battery 3 rises, the rotary switch SW is connected to the resistors R2,.
5A, the resistance of the resistor 4A is changed to the value shown in FIG.
As shown in FIG.

Then, the resistance value is reduced stepwise according to the rise of the capacitor battery voltage Vc, and finally, the lead battery 2 and the capacitor battery 3 are directly connected without turning the rotary switch SW of the resistor 4A through a resistor. When the capacitor battery voltage Vc reaches the voltage Vmax at the time of full charge, the charging is completed.

In this embodiment, similarly to the above-described first embodiment, it is possible to prevent a decrease in charging efficiency and to shorten the charging time. Is switched to reduce the resistance value, which is advantageous in terms of heat resistance and durability compared to a sliding-type variable resistor such as the resistor 4 in the first embodiment described above. It can correspond to a large current power supply system. In addition, the capacitor battery 3
Is the voltage at which charging is completed, the resistor 4A can be set to substantially zero resistance, and the power of the capacitor battery 3 can be used to the maximum.

As shown in FIG. 6 or 7, instead of a voltage measuring device 5 for measuring the voltage of the capacitor battery 3, a Hall element is provided between the capacitor battery 3 and the resistor 4 (resistor 4A). A current measuring device 5A may be provided, and the current value measured by the current measuring device 5A is taken into the charge controller 10, and the voltage of the capacitor battery 3 is calculated by calculation. In this case, even if an excessive current occurs during charging, the excessive current can be detected as soon as possible, which can contribute to fail-safe.

[0030]

As described above, according to the present invention, when a capacitor battery is charged by a lead battery, the resistance value of a resistor interposed between the lead battery and the capacitor battery is changed by the voltage of the capacitor battery. Since the charge current is decreased in accordance with the rise, it is possible to prevent a decrease in the charging current with the progress of charging, to avoid a decrease in charging efficiency, and to obtain excellent effects such as a reduction in charging time.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a charging device according to a first embodiment of the present invention.

FIG. 2 is a flowchart of a charging control routine according to the first embodiment;

FIG. 3 is an explanatory diagram showing resistance setting according to the first embodiment;

FIG. 4 is an overall configuration diagram of a charging device according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing resistance setting according to the first embodiment;

FIG. 6 is an overall configuration diagram of a charging device using a current measuring device.

FIG. 7 is an overall configuration diagram of another charging device using a current measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Charging device 2 ... Lead battery 3 ... Capacitor battery 4,4A ... Resistor 5 ... Voltage measuring instrument 10 ... Charge controller

Claims (3)

[Claims] 1. A battery charging device for a power supply system comprising a lead battery and a capacitor battery, wherein the capacitor battery is charged by the lead battery, the battery charger being interposed between the lead battery and the capacitor battery, A resistor whose resistance value can be changed by an input; and control means for measuring the voltage of the capacitor battery and performing an operation output for decreasing the resistance value of the resistor in accordance with an increase in the voltage of the capacitor battery. A battery charger characterized by the above-mentioned. 2. The battery charger according to claim 1, wherein a resistance value of the resistor is continuously variable. 3. The battery charger according to claim 1, wherein a resistance value of the resistor is variable in a stepwise manner.